U.S. Pat. No. 4,817,828 discloses an apparatus for inflating an inflatable vehicle occupant restraint such as an air bag. The apparatus includes an inflator which comprises a source of gas for inflating the air bag. A body of ignitable gas generating material is contained in the inflator. The gas generating material is ignited when the vehicle experiences a condition that indicates the occurrence of a collision for which inflation of the air bag is desired. The collision-indicating condition may comprise, for example, the occurrence of a predetermined amount of vehicle deceleration. As the gas generating material burns, it generates a large volume of gas which is directed to flow from the inflator into the air bag to inflate the air bag. When the air bag is inflated, it extends into the vehicle occupant compartment to restrain an occupant of the vehicle from forcefully striking parts of the vehicle.
The inflator disclosed in the '828 patent has a cylindrical housing with a combustion chamber in which the body of gas generating material is contained. The housing has a tubular outer wall which is closed at its axially opposite ends by a pair of circular end walls. The end walls extend diametrically across the open ends of the tubular wall. Each end wall has an annular peripheral flange, and is held in place by a respective end portion of the tubular wall which is crimped around the flange. The closed ends of the housing are sealed by a pair of elastomeric sealing rings. Each of the sealing rings is located inside the housing adjacent to a respective one of the end walls.
The inflator disclosed in the '828 patent further includes an igniter assembly which is actuated in response to the collision-indicating condition. When the igniter assembly is actuated, a pyrotechnic material in the igniter assembly is ignited and emits combustion products which, in turn, ignite the gas generating material. The pyrotechnic material is contained in a relatively narrow cylindrical igniter housing. The igniter housing is screwed through a threaded opening at the center of one of the circular end walls, and is thus supported on the axis of the inflator at one end of the combustion chamber.